Klebsiella pneumoniae and Enterobacter are microorganisms which occur in urine, feces, throat, etc. The presence of K. pneumoniae in urine is a reliable indicator of pneumonia. If Klebsiella or Enterobacteris present in a given sample of urine, it is also possible that Escherichia Coli and other coliform organisms are also present in the sample.
We desire to determine the presence of either Klebsiella or Enterobacter because these organisms, while distinct, are closely related and difficult to distinguish without extensive testing and indicate the presence of similar infections.
The medium of this invention is an improved medium designed for use with the optical detection system disclosed in U.S. applications Ser. Nos. 255,533 filed May 22, 1972 now abandoned and 461,249 filed Apr. 16, 1974 now U.S. Pat. No. 3,963,355 and in the improved devices disclosed and claimed in applications filed on even date herewith by Charles, Jones, Staples and Wiegner entitled AUTOMATED MICROBIAL ANALYZER and MACHINE AND PROCESS FOR READING CARDS CONTAINING MEDICAL SPECIMENS. These applications describe mechanism and apparatus suitable for analyzing specimens for specific microorganisms using a plastic tray or card which contains a series of dried culture media contained in separate but connected cells, each of the media being specific to a single organism. When the sample is inserted into the card, mixed with the media in the cells, and incubated in the machine, the organism (or organisms) present in the specimen interacts with the culture medium specific to that organism and produces a change in the medium which is read by the machine to indicate the presence of the organism. The change in the medium involves a change in the light transmitting properties of the medium, i.e., a color change or change in turbidity. The change may be caused by metabolic activity of the organism, which, for example, may cause production of acid and a change in pH which causes a color change in a pH sensitive indicator in the medium. The change in the light transmitting properties of the medium also could be caused by a precipitate forming in the medium due to metabolic activity of the organism or it could be caused by growth of the organism.
The specific media designed for use in the aforesaid cards are all designed to favor growth of one microorganism and to inhibit growth of other organisms, are capable of being freeze dried, and can function in the low 0.sub.2 environment of the wells of the card described in detail in said copending applications AUTOMATED MICROBIAL ANALYZER and MACHINE AND PROCESS FOR READING CARDS CONTAINING MEDICAL SPECIMENS.
We have discovered a medium which can selectively identify Klebsiella and Enterobacter organism in urine when the medium is placed in the wells of the cards described in application AUTOMATED MICROBIAL ANALYZER.
Positive results are indicated by means of precipitation of bile salts (sodium desoxycholate) and ricinoleic acid, which causes a change in the light transmitting character of the medium, which change is read by the mechanism described in application AUTOMATED MICROBIAL ANALYZER. The entire test can be completed within 12 - 18 hours, whereas current methods of detection require from about 36 to about 48 hours.
SUMMARY
This invention involves a broth medium for the detection of Klebsiella and Enterobacter in urine. The medium will detect the presence of Klebsiella pneumoniae in particular.
The medium contains sources of carbon, sources of nitrogen, sources of vitamins, bile salts mixture, E. coli inhibitors, gram-negative organism inhibitors and Klebsiella growth promoter.
The novelty of the invention lies in the use of 3-(.alpha.-acetonylbenzyl)-4-hydroxycoumarin and 2,4 dinitrophenyl hydrazone of .alpha.-Ketoglutaric acid, which operate to inhibit growth of E. Coli and promote growth of Klebsiella. The relatively high pH of the medium also helps to suppress growth of other unwanted organisms.
Also novel is the combination of Bile Salts Mixture and the ricinoleic acid indicator which allows use of the medium in the mechanism shown in application for AUTOMATED MICROBIAL ANALYZER, by means of which the presence of Klebsiella or Enterobacter is detected by precipitation in the medium.